Counterbalancing sheet feeding mechanism



March 16, 1965 A. F. SHIELDS 3,173,532

COUNTERBALANCING SHEET FEEDING MECHANISM Filed Jan. 7, 1963 3 Sheets-Sheet 1 INVENTOR. ALJEQT F SW LMF BY Qrmaz :70, 15105 3 6:00 {BF/M March 16, 1965 A. F. SHIELDS 3,173,632

COUNTERBALANCING SHEET FEEDING MECHANISM Filed Jan. '7, 1963 3 Sheets-Sheet 2 INVENTOR. Alana-er E JAVA as" March 16, 1965 A. F. SHIELDS COUNTERBALANCING SHEET FEEDING MECHANISM 3 Sheets-Sheet 3 Filed Jan. 7, 1963 BY orta; :Me, 59652, Q24 ffrmv $73,382 Patented Mar. 16 1965 3,173,682 COUNTERBALANCING SHEET FEEDING MECHANISM Albert F. Shields, 43 Exeter St., Forest Hills, N.Y. Filed Jan. 7, 1963, Ser. No. 249,738 18 Claims. (Cl. 271-44) The instant invention relates to apparatus for handling corrugated board and more particularly relates to a sheet feeding mechanism having counterbalancing means incorporated therein.

In my United States Patent No. 2,583,713, issued January 29, 1952, there is described a feeding mechanism for folding machines. The folding machine is intended to receive scored and slotted box blanks and fold the side panels of these blanks inwardly to form folded tubular boxes. The feeding mechanism is provided with a hopper holding a stack of blanks. The stack is replenished by adding blanks to the top th-.-reof while blanks are removed one at a time from the "ottom of the stack by spring feeders which engage the trailing edge of the bottom-most blank and convey this blank forward until the leading edge of this blank is engaged by feed rollers. The rollers in turn deliver the blank to the folding mechanism. The spring feeders are mounted to a feed slat which reciprocates along the feed path of the blanks.

In order to construct the feeding mechanism so that it may be adjusted for the feeding of short blanks it is necessary that the feed slat have a short stroke. Further, it is necessary for the speed of the blank being fed to equal the speed of the feed rollers at the time the forward edge of the blank engages the feed rollers. If the blank is not up to the speed of the feed rollers at that time, incorrect tuning, i.e. register of the blank in the machine, will occur thereby resulting in the production of faulty boxes. Thus, the feed mechanism must provide a short high speed stroke. After the blank is engaged by the feed rollers the feed slat must first be decelerated and its direction of travel must be reversed.

This type of rapid acceleration and deceleration in linear reciprocating motion imposes high stresses on all working parts especially during deceleration with a resultant relatively rapid wear thereof.

In order to minimize the mechanical stresses described above the instant invention provides a counterbalancing means in the form of a rocking arm freely mounted to the rock shaft which drives the feed slat. The drive for the rocking arm is arranged in such a manner that during the period when the feed slat is being decelerated' the rocking arm is being accelerated.

This is accomplished in a simple manner by providing a shaft which rotates at constant angular velocity for each revolution thereof. Two angularly displaced drive pins are mounted eccentric to the drive shaft and are driven thereby at a constant angular velocity. One of the pins acting through a slotted drive arm connection imparts rocking motion to the rock shaft. While the other pin acting through a slotted connection to a rocking or counterbalancing arm rocks this arm about the rock shaft as a center.

The weight of the counterbalancing arm and the displacement between the drive pins are chosen so as to minimize vibration of the system. It has been found that by displacing the drive pins approximately 90 from each other satisfactory operation is obtained.

Accordingly, a primary object of this invention is to provide a sheet feeding mechanism construction which will have a much greater life than similar prior art de vices.

Another object is to provide a sheet feeding mechanism having novel counterbalancing means to minimize vibration.

Still another object is to provide a sheet feeding mechanism, having a feed slat with a short rapid feed stroke, with a counterbalancing mechanism.

A further object is to provide a counterbalancing mechanism which is accelerating while the drive mechanism is decelerating thereby resulting in the substantial elimination of vibration.

These objects as well as further objects of this invention shall become readily apparent after reading the following description of the accompanying drawings in which:

FIGURE 1 is a side elevation of a sheet feeding mechanism including a counterbalancing means constructed in accordance with the teachings of the instant invention.

FIGURE 2 is a side elevation of the rock shaft for driving the feed slat and the elements which impart motion to the rock shaft.

FIGURE 3 is a cross-section taken through lines 3-3 of FIGURE 2 looking in the direction of arrows 3-3.

FIGURE 4 is a side elevation of the counterbalancing elements looking in the direction of arrows 4-4 of FIG- URE 3.

FIGURE 5 is an expanded perspective in somewhat schematic form illustrating the driving means for the feed slat and the counterbalancing elements of the apparatus.

FIGURE 6 illustrates the velocity pattern of the feed slat.

Now referring to the figures and more particularly to FIGURE 1. The blanks in stack 10 are fed one at a time between feed rolls 11, 11a for delivery to a folding machine (not shown) or other apparatus which will perform operations on the blanks. Stack 10 is shown as resting upon feeding mechanism bed 80. The forward end of stack 10 rests against front gage 12 while the rear of stack 10 is maintained in position by rear gage 13. The lateral position of stack 10 on bed is established by two side gages 14 only one of which is shown in FIGURE 1. The forward edge of table 11 is provided with bar 31 which overlies table 11 and is spaced therefrom to form recess 32 which is adapted to receive spring feeders 33, mounted to feed slat 34, when slat 34 is moved to the right with respect to FIGURE 1.

The bottom blank in stack 10 is fed to the right by spring feeders 33 through space 35 between front gage 12 and bar 31. Space 35 is adjusted to permit one of the blanks to pass through while holding back the re mainder of stack 10. After passing through space 20 the blank is pushed by spring feeders 33 between the upper and lower feed rolls 11 and 11a which convey the blank forward in a manner well-known to the art.

Feed slat 34 extends across bed 11 at right angles to the blank feed path with the ends of slat 34 being secured to carriage 41 which is mounted on rollers 42, 43, 44 guided for movement in a direction parallel to the feed path of the blanks in stack 10.

Reciprocating motion is imparted to carriage 41 by a mechanism driven by wheel-like member 45 keyed to stub shaft 46. The periphery of member 45 is provided with gear teeth 47 which are in mesh with the teeth of a driving gear 81. Driving gear 81 meshes also with gear 82 which in turn meshes with gear 82 keyed to feed roll 11a. As best seen in FIGURE 3, stub shaft 46 is mounted for rotation in bearings 48, 49 held by housing 98 which is secured to frame 97 by fasteners 96. Pin 51 projects from the plane of member 45 in a direction parallel to shaft 46. Pin 51 is eccentric with respect to shaft 46 and carries roller 52 which is disposed within slot 53 of drive crank 54 between bearing plates 55, 56. Drive crank 54 is keyed to rock shaft 50. Thus, it is seen is moving opposite to the feed direction.

that the constant speed angular motion of shaft 46 is caused to impart a rocking motion to rock shaft 50.

Shaft 50 is keyed to a pair of parallel arms 57 at one end of these arms (FIGURE 5). Arms 57 are disposed at opposite sides of carriage 41. The other ends of arms 57 are joined at pins 58 to a pair of parallel connecting links 59, The other ends of connecting links 59 are joined at pins 62 to carriage 41. Thus, it is seen that the rocking motion of shaft 50 is transmitted to carriage 41 causing the latter to reciprocate in a path parallel to the feed path of blanks leaving stack 10.

It will be appreciated by those skilled in the art that equal angular movements of driving roller 52 will not always bring about equal angular movements of rocker arm 54. More specifically, with member 45 rotating in the direction of arrow A, FIGURE 2 and the direction of sheet feeding being indicated by arrow B in FIGURE 2, a greater angular motion will be imparted to rock shaft 50 for positions of roller 52 closer to shaft 50 than for those positions of roller more remote from shaft 50. Naturally, the angular motions to be compared are those motions equidistant from a line of symmetry passing through shafts 46 and 50. Because of this carriage 41, hence feed slat 34, will have a speed pattern as illustrated in FIGURE 6.

Points on the curve above the zero line indicate that the feed slat 34 is moving in the feed direction while those points below the zero line indicate that the feed slat The bottom sheet in the stack is engaged by spring feeders 33 at substantially point A on the curve. At point B on the curve, feed slat velocity substantially equals or is slightly greater than the peripheral velocity of feed roller 11. This is the point at which the bottom sheet being fed from stack engages feed rollers 11, 11a. Thereafter, and until point C, feed slat 34 decelerates. slat 34 moves in the reverse direction.

It is noted that slat velocity at point B exceeds the velocity of the slat at any point in the return stroke. It is also seen that the feed slat must be accelerated from a standstill position at point A to maximum velocity at point B in a very small part of the cycle, and that the deceleration from maximum speed to zero speed at point C alsotakes place in only a short portion of the cycle. Because of these rapid accelerations and decelerations of feed slat 34 and the drive elements therefor, all of these elements are subjected to severe mechanical stresses when machines are run at elevated speeds. It is found in practice that deceleration tends to cause more shock than acceleration possibly due to the effect of backlash and running clearances.

In order to substantially reduce these stresses the instant invention provides counterbalancing arm 70 which is mounted to freely pivot about rock shaft 50. Arm 70 is provided with slot 71 which receives roller 72 between bearing plates 73, 74. Roller 72 is mounted to pin 75 extending from the plane of wheel 76 which is keyed to stub shaft 46. Pin 75 is parallel to stub shaft 46 and is eccentric with respect thereto. Thus, it is seen that the constant angular speed of shaft 46 is transmitted to arm 70 so as to cause a rocking motion thereof in the manner previously explained in connection with drive arm 54.

Pins 51 and 75 are angularly spaced about shaft 46 as a center. In the embodiment illustrated in the drawings, this displacement is substantially a 90 lag of pin 75, since it is seen that the counterbalance arm must be at a point corresponding to C while the drive arm is at a point corresponding to B. It has been found that with this displacement and with an appropriately weighted member 79 carried by arm 70, counterbalancing forces are established which effectively reduce the forces previously described. With the 90 displacement in the direction indicated, deceleration of drive arm 54 occurs at a time when counterbalancing arm 70 is being accelerated. Averaged over a complete cycle the opposing accelerating Between points C and A and decelerating forces generated through the rocking motion of arms 54 and 70 and the elements connected thereto, tend to cancel one another and as a result the mechanism is not subjected to the severe mechanical shocks characteristic of similar prior art devices.

Thus, this invention provides a novel, reliable, relatively inexpensive means for improving the running smoothness and extending the life of a sheet feeding mechanism which includes a reciprocating v feed slat. Naturally, the instant invention may be applied to other types of mechanisms in which there is a reciprocated element which is rapidly accelerated and decelerated during each cycle therein. A

Although there has been described a preferred embodiment of this novel invention, many variations and modifications will now be apparent to those skilled in the art. Therefore, this invention is to be limited, not by the specific disclosure herein, but only by the appending claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

1. A device of the class described comprising a driving shaft rotatable at constant angular speed, a rock driving shaft, first means keyed to said rock shaft and operatively connected to said driving shaft in a manner such that said rock driving shaft is caused to pivot back and forth about its longitudinal axis at a speed which varies within a complete revolution of said driving shaft with the forward pivoting angular velocity exceeding the backward pivoting angular velocity, second means including a counterbalancing arm freely mounted to said rock shaft for pivotal movement thereabout and operatively connected to said driving shaft to be pivoted back and forth at a speed which varies within a complete revolution of said driving shaft with the forward pivoting angular velocity of said counterbalancing arm exceeding the backward pivoting angular velocity of said counterbalancing arm.

2. A device as set forth in claim 1 in which the pivotal movement of said counterbalancing arm is out of phase with the pivotal movement of said rock shaft.

3. A device as set forth in claim 1 in which the pivotal movement of said counterbalancing arm lags behind the pivotal movement of said rock shaft by substantially less than 180?.

4. A device as set forth in claim 1 in which the pivotal movement of said counterbalancing arm lags the pivotal movement of said rock shaft by approximately 5. A device as set forth in claim 1 in which the first means comprises a drive arm, a first pin and a second pin each eccentric with respect to said shaft and driven at constant angular velocity thereby with said shaft as a center, a first slotted connection joining said first pin to said drive arm and a second slotted connection joining said second pin to said counterbalancing arm.

6. A device as set forth in claim 5 in which the pins are angularly displaced from each other about said shaft as a center whereby the pivotal movement of said counterbalancing arm is out of phase with the pivotal movement of said rock shaft.

7. A device as set forth in claim 5 in which the pivotal movement of said counterbalancing arm lags behind the pivotal movement of said rock shaft by substantially less than 8. A device as set forth in claim 5 in which the pins are displaced approximately 90 from each other about said shaft as a center in such operative positions that the pivotal movement of said counterbalancing arm lags the pivotal movement of said rock shaft by approximately 90.

9. A device of the class described comprising a driving shaft rotatable at constant angular speed, a rock driving shaft, first means keyed to said rock shaft and operatively connected to said driving shaft in a manner such that said rock driving shaft is caused to pivot back and forth about its longitudinal axis at a speed which varies within a complete revolution of said driving shaft with the forward pivoting angular velocity exceeding the backward pivoting angular velocity, second means including a counterbalancing arm freely mounted to said rock shaft for pivotally movement thereabout and operatively connected to said driving shaft to be pivoted back and forth at a speed which varies within a complete revolution of said driving shaft with the forward pivoting angular velocity of said counterbalancing arm exceeding the backward pivoting angular velocity of said counterbalancing arm, a sheet feeding slat means extending generally parallel to said rock shaft, means for guiding said slat means for reciprocating linear motion, and means operatively connecting said slat means to said rock shaft whereby motion of said rock shaft drives said slat so that its movement in sheet feeding direction is for a substantially shorter period of time than its movement in the opposite direction.

10. A device as set forth in claim 9 the pivotal movement of said counterbalancing arm is out of phase with the pivotal .movement of said rock shaft.

11. A device as set forth in claim 9 the pivotal movement of said counterbalancing arm lags the pivotal movement of said rock shaft by approximately 90.

12. A device as set forth in claim 9 in which the first means comprises a drive arm, a first pin and a second pin each eccentric with respect to said shaft and driven at constant angular velocity thereby with said shaft as a center, a first slotted connection joining said first pin to said drive arm and a second slotted connection joining said second pin to said counterbalancing arm.

13. A device as set forth in claim -12 in which the pins are angularly displaced from each other about said shaft as a center whereby the pivotal movement of said counterhalancing arm is out of phase with the pivotal movement of said rock shaft.

14. A device as set forth in claim 12 in which the pivotal movement of said counterbalancing arm lags behind the pivotal movement of said rock shaft by substantially less than 180.

15. A device as set forth in claim 12 in which the pins are displaced approximately from each other about said shaft as a center in such operative positions that the pivotal movement of said counterbalancing arm lags the pivotal movement of said rock shaft by approximately 90.

16. A device as set forth in claim 2 in which the counterbalancing arm is accelerating in its forward motion at a time when said rock shaft is decelerating in its forward direction. I

17. A device as set forth in claim 6 in which the counterbalancing arm is accelerating in its forward motion at a time when said rock shaft is decelerating in its forward direction.

18. A device as set forth in claim 10 in which the counterbalancing arm is accelerating in its forward motion at a time when said rock shaft is decelerating in its forward direction.

References Cited by the Examiner UNITED STATES PATENTS ERNEST A. FALLER, Primary Examiner. RAPHAEL M. LUPO, Examiner.

7/61 Saltz et al 27 l-29 v 

1. A DEVICE AT THE CLASS DESCRIBED COMPRISING A DRIVING SHAFT ROTATABLE AT CONSTANT ANGULAR SPEED, A ROCK DRIVING SHAFT, FIRST MEANS KEYED TO SAID ROCK SHAFT AND OPERATIVELY CONNECTED TO SAID DRIVING SHAFT IN A MANNER SUCH THAT SAID ROCK DRIVING SHAFT IS CAUSED TO PIVOT BACK AND FORTH ABOUT ITS LONGITUDINAL AXIS AT A SPEED WHICH VARIES WITHIN A COMPLETE REVOLUTION OF SAID DRIVING SHAFT WITH THE FORWARD PIVOTING ANGULAR VELOCITY EXCEEDING THE BACKWARD PIVOTING ANGULAR VELOCITY, SECOND MEANS INCLUDING A COUNTERBALANCING ARM FREELY MOUNTED TO SAID ROCK SHAFT FOR 